1. Field of the Invention
The invention relates to a light source module. More particularly, the invention relates to a light source module having superior light emitting efficiency.
2. Description of Related Art
Along with the flourishing developments of flat panel display technology, liquid crystal displays (LCDs) have played a major role in the mainstream display market and are widely used in people's daily lives to replace the traditional cathode ray tube (CRT) display. Since LCD panels in LCDs are not self-luminescent, light source modules are employed to provide backlight source. According to the placement of the light-emitting devices in a light source module, the light source module is categorized into a direct type light source module and a side incident light source module, where the side incident light source module is able to guide light from the side to the front so as to form a surface light source by employing a light guide plate (LGP) as the critical component.
FIG. 1A is a schematic top view of a side incident light source module. FIG. 1B illustrates a schematic cross-sectional view taken along line AA′ of the light source module shown in FIG. 1A. Referring to FIGS. 1A and 1B, a light module 100 includes a light source 110, a light guide plate (LGP) 120, a reflector 130, and an optical diffuser 140. The LGP 120 has an upper surface 122, a lower surface 124 opposite to the upper surface 122, and a light entering surface 126 connecting the upper surface 122 and the lower surface 124. The upper surface 122 and the lower surface 124 are both perpendicular to the light entering surface 126, for example.
In the light source module 100, the light entering surface 126 of the LGP 120 is usually disposed with the light source 110. The light source 110 is a light emitting diode (LED) or a cold cathode fluorescent lamp (CCFL). The lower surface 124 of the LGP 120 includes a plurality of protrusion portions 121, where each of the protrusion portions 121 has the same height. After a beam 112 from the light source 110 passes through the light entering surface 126 and enters the LGP 120, since the total reflection of the beam 112 in the LGP 120 is disrupted by the foregoing protrusion portions 121, the beam 112 in the LGP 120 is guided and emitted from the upper surface 122 uniformly to exit the LGP 120.
In general, the reflector 130 is usually disposed on the lower surface 124 of the LGP 120 in the light source module 100, so that a portion of the beam 112 passing through and exiting the lower surface 124 is reflected back into the LGP 120 for increasing the backlight brightness of the light source module 100. Moreover, to enhance the overall backlight uniformity of the light source module 100, the optical diffuser 140 is further disposed on the upper surface 122 of the LGP 120 in the light source module 100 so as to enhance backlight uniformity.
Nonetheless, the overall backlight brightness enhancement remains limited even when the light source module 100 adopts light reflective structures (the protrusion portions 121) of the LGP 120 illustrated in FIG. 1. Therefore, manufacturers work on designing a micro-structure on the LGP 120 which can further increase the backlight brightness of the light source module.